MOD Portland Bill

The MOD Portland Bill site is on the Isle of Portland in Dorset. The site was chosen in the 1960s for its magnetic cleanliness, making it ideal for magnetic measurement. Portland stone is non-magnetic and because the site is remote from any magnetic disturbance such as heavy traffic, very small magnetic fields from equipment can be measured with absolute certainty. The Land Magnetic Range (LMR) can be used to magnetically assess any item, but its primary role is to test items used on Mine Countermeasure Vessels (MCMV) and Explosive Ordnance Disposal (EOD) equipment.

The LMR is capable of simulating the Earth’s ambient magnetic field found at any location on Earth, and measuring the effect on the test object. The Earth’s field can be reduced to zero, or be broken into its vertical and horizontal components.

Magnetic compasses are tested in the Compass Test Centre, which is also on site. This unique completely magnetically transparent facility is notified and approved by the Maritime and Coastguard Agency and is the only accredited centre for Type Approval of Magnetic Compasses and Binnacles in the UK.

The Special Magnetic Effects Area has coils that can be used to demagnetise items, magnetise items (EOD Idealisation), and enable Magnetic Susceptibility tests to be carried out on submarine equipment that might be affected by heavy treatment fields.

Magnetic surveys are offered to support areas used in the production, maintenance and storage of MCMV & EOD equipment. Compass Base surveys on airfields are also supported by the team at MOD Portland Bill.

The site is also home to an Electronic Warfare Calibration centre (Calfac), which can test the performance of RADAR Electronic Support Measures (RESM) fitted on RN vessels (ships & aircraft)